a) Field of the Invention
The present invention relates to a delay line for delaying image information, and more particularly to driving a delay line using a semiconductor charge coupled device (CCD) for delaying image information.
b) Description of the Related Art
Delay lines are used in televisions in order to obtain a high quality of images while deriving color and luminance information from video signals. The delay time and delay characteristics are dependent upon the structure and material of a delay line. In place of a glass delay line having some problem of delay characteristics, CCD semiconductor delay lines have been used for delaying an input signal by 1 H (or 0.5 H).
FIG. 5 shows the structure of such a CCD semiconductor delay line. A CCD semiconductor delay line 101 is supplied with power sources VDD and VSS. An input signal 102, a reference signal 103 and a DC bias are also supplied to the delay line 101. The input signal is delayed by some period determined by the frequency of the reference signal 103 and the number of stages of the delay line, to provide a delayed output signal 105.
Such a CCD semiconductor delay line has excellent characteristics. However, it is necessary to externally supply a reference signal. The analog circuit system for a video signal is required to have a circuit for generating a clock signal.